Quickstart Guide
================

This guide gives an overview of dnsdist features and operations.

Running in the Foreground
-------------------------

After :doc:`installing <install>` dnsdist, the quickest way to start experimenting is launching it on the foreground with::

   dnsdist -l 127.0.0.1:5300 9.9.9.9 2620:fe::fe 2620:fe::9

This will make dnsdist listen on IP address 127.0.0.1, port 5300 and forward all queries to the three listed IP addresses, with a sensible balancing policy.

``dnsdist`` Console and Configuration
-------------------------------------

Here is more complete configuration:

.. md-tab-set::

    .. md-tab-item:: YAML

      Store as ``dnsdist.yml``:

      .. code-block:: yaml

        backends:
          - address: "2001:db8::1"
            protocol: Do53
            queries_per_second: 1
          - address: "2001:db8::2"
            protocol: Do53
            queries_per_second: 1
          - address: "[2001:db8::3]:5300"
            protocol: Do53
            queries_per_second: 10
          - address: "[2001:db8::4]"
            name: "dns1"
            protocol: Do53
            queries_per_second: 10
          - address: "192.0.2.1"
            protocol: Do53
        load_balancing_policies:
          default_policy: "firstAvailable"

    .. md-tab-item:: Lua

      The ``lua`` equivalent, which was the default before 2.1, uses the :func:`newServer`
      function to add a backend server to the configuration:

      .. code-block:: lua

        newServer({address="2001:db8::1", qps=1})
        newServer({address="2001:db8::2", qps=1})
        newServer({address="[2001:db8::3]:5300", qps=10})
        newServer({address="2001:db8::4", name="dns1", qps=10})
        newServer("192.0.2.1")
        setServerPolicy(firstAvailable) -- first server within its QPS limit


Now run dnsdist again, reading this configuration::

  $ dnsdist -C dnsdist.yml --local=0.0.0.0:5300
  Marking downstream [2001:db8::1]:53 as 'up'
  Marking downstream [2001:db8::2]:53 as 'up'
  Marking downstream [2001:db8::3]:5300 as 'up'
  Marking downstream [2001:db8::4]:53 as 'up'
  Marking downstream 192.0.2.1.:53 as 'up'
  Listening on 0.0.0.0:5300
  >

You can now send queries to port 5300, and get answers::

  $ dig -t aaaa powerdns.com @127.0.0.1 -p 5300 +short +nocookie
  2001:888:2000:1d::2

Note that dnsdist dropped us in a prompt above, where we can get some statistics::

  > showServers()
  #   Address                   State     Qps    Qlim Ord Wt    Queries   Drops Drate   Lat Pools
  0   [2001:db8::1]:53             up     0.0       1   1  1          1       0   0.0   0.0
  1   [2001:db8::2]:53             up     0.0       1   1  1          0       0   0.0   0.0
  2   [2001:db8::3]:5300           up     0.0      10   1  1          0       0   0.0   0.0
  3   [2001:db8::4]:53             up     0.0      10   1  1          0       0   0.0   0.0
  4   192.0.2.1:53                 up     0.0       0   1  1          0       0   0.0   0.0
  All                                     0.0                         1       0

:func:`showServers()` is usually one of the first commands you will use when logging into the console. More advanced topics are covered in :doc:`guides/console`.

Here we also see our configuration: 5 downstream servers have been configured, of which the first 4 have a QPS limit (of 1, 1, 10 and 10 queries per second, respectively).

The final server has no limit, which we can easily test::

  $ for a in {0..1000}; do dig powerdns.com @127.0.0.1 -p 5300 +noall +nocookie > /dev/null; done

::

  > showServers()
  #   Address                   State     Qps    Qlim Ord Wt    Queries   Drops Drate   Lat Pools
  0   [2001:db8::1]:53             up     1.0       1   1  1          7       0   0.0   1.6
  1   [2001:db8::2]:53             up     1.0       1   1  1          6       0   0.0   0.6
  2   [2001:db8::3]:5300           up    10.3      10   1  1         64       0   0.0   2.4
  3   [2001:db8::4]:53             up    10.3      10   1  1         63       0   0.0   2.4
  4   192.0.2.1:53                 up   125.8       0   1  1        671       0   0.0   0.4
  All                                   145.0                       811       0

Note that the first 4 servers were all limited to near their configured QPS, and that our final server was taking up most of the traffic.
No queries were dropped, and all servers remain up.

Changing Server Settings
~~~~~~~~~~~~~~~~~~~~~~~~

The servers from :func:`showServers` are numbered, :func:`getServer` is used to get this :class:`Server` object to manipulate it.

To force a server down, try :attr:`Server:setDown()`::

  > getServer(0):setDown()
  > showServers()
  #   Address                   State     Qps    Qlim Ord Wt    Queries   Drops Drate   Lat Pools
  0   [2001:db8::1]:53           DOWN     0.0       1   1  1          8       0   0.0   0.0
  ...

The ``DOWN`` in all caps means it was forced down.
A lowercase ``down`` would've meant that dnsdist itself had concluded the server was down.
Similarly, :meth:`Server.setUp()` forces a server to be up, and :meth:`Server.setAuto` returns it to the default availability-probing.

To change the QPS for a server, use :meth:`Server.setQPS`::

  > getServer(0):setQPS(1000)

Restricting Access
------------------

By default, dnsdist listens on ``127.0.0.1`` (not ``::1``!), port 53.

To listen on a different address, use the ``-l`` command line option (useful for testing in the foreground).
Listen addresses can also be set in the configuration files:


.. md-tab-set::

    .. md-tab-item:: YAML

      In the YAML configuration, configure ``binds``.

      .. code-block:: yaml

        acl:
          - "192.0.2.0/28"
          - "2001:db8:1::/56"
          - "2001:db8:2::/56"
        binds:
          - listen_address: "192.0.2.53"
            protocol: Do53
          - listen_address: "[::1]:5300"
            protocol: Do53

    .. md-tab-item:: Lua

      :func:`setLocal` and :func:`addLocal` are use to create listen sockets.
      Adding network ranges to the :term:`ACL` is done with the :func:`setACL` and :func:`addACL` functions:

      .. code-block:: lua

        setLocal('192.0.2.53')      -- Listen on 192.0.2.53, port 53
        addLocal('[::1]:5300') -- Also listen on ::1, port 5300

        setACL({'192.0.2.0/28', '2001:db8:1::/56'}) -- Set the ACL to only allow these subnets
        addACL('2001:db8:2::/56')                   -- Add this subnet to the existing ACL

Before packets are processed they have to pass the ACL, which helpfully defaults to :rfc:`1918` private IP space.
This prevents us from easily becoming an open DNS resolver.

Securing the path to the backend
--------------------------------

dnsdist has always been designed as a load-balancer placed in front of authoritative or recursive servers,
assuming that the network path between dnsdist and these servers is trusted.

If dnsdist is instead intended to be deployed in such a way that the path to its backend is not secure, the
UDP protocol should not be used, and 'TCP-only', DNS over TLS and DNS over HTTPS protocols used instead, as
supported since 1.7.0.

For more details, please look at the :doc:`../guides/downstreams` guide.

More Information
----------------

Following this quickstart guide allowed you to set up a basic balancing dnsdist instance.
However, dnsdist is much more powerful.
See the :doc:`guides/index` and/or the :doc:`advanced/index` sections on how to shape, shut and otherwise manipulate DNS traffic.
